package com.jxmobi.util.algorithm;

import com.jxmobi.util.StringUtils;

import java.util.Objects;

public class AlgorithmUtils {

	private static class Crc16 {
		static int[] table = {
				0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
				0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
				0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
				0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
				0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
				0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
				0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
				0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
				0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
				0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
				0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
				0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
				0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
				0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
				0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
				0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
				0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
				0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
				0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
				0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
				0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
				0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
				0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
				0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
				0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
				0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
				0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
				0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
				0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
				0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
				0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
				0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040,
		};

		public static int getCrc(byte[] bytes) {
			int crc = 0xffff;
			for (byte b : bytes) {
				crc = (crc >>> 8) ^ table[(crc ^ b) & 0xff];
			}
			return crc;
		}
	}

	/**
	 *  将给定的 byte 进行 crc16 位检验
	 * @param buffer 字节数组
	 * @return crc 码
	 */
	public static int crc16_8005(final byte[] buffer) {
		return Crc16.getCrc(buffer);
	}

	/**
	 *  将给定的 byte 进行 crc16 位检验
	 * @param buffer 字节数组
	 * @return crc 码
     */
	public static int crc16(final byte[] buffer) {
		if (buffer == null)
			throw new IllegalArgumentException("parameter must be provided");

		int crc = 0xFFFF;

		for (byte aBuffer : buffer) {
			crc = ((crc >>> 8) | (crc << 8)) & 0xffff;
			crc ^= (aBuffer & 0xff);//byte to int, trunc sign
			crc ^= ((crc & 0xff) >> 4);
			crc ^= (crc << 12) & 0xffff;
			crc ^= ((crc & 0xFF) << 5) & 0xffff;
		}
		crc &= 0xffff;
		return crc;

	}

	/**
	 * 异或算法获取增加校验位字符
	 * 
	 * @author aixianshang
	 * @date 2015年9月14日 上午11:26:08
	 * @param str 准备参与异或运算的字符串需满足如下格式
     *            [tst:1;uuid:s001;com:1]
	 * @return
	 */
	public static String xorAlgorithm(String str) {
		int _index=str.length()-1;
		String result=str.substring(0,_index);
		String xor=xor(result);
		result=result+xor+"]";
		return result;
	}

	/**
	 * tbox传输数据进行异或解析校验数据完整性
	 * 
	 * @author aixianshang
	 * @date 2015年9月14日 上午11:26:40
	 * @param str
	 * @return 返回空表示异或校验不匹配
	 */
	public static String xorAnalysis(String str) {
		if (StringUtils.isEmpty(str)) {
			return "";
		}
		int _index=str.length();
		String laststr=str.substring(_index-1);
		if(!"]".equals(laststr)){
			return "";
		}
		String paritystr=str.substring(_index-3,_index-1);
		//异或结果
		String result=str.substring(0,_index-3);
		String xor=xor(result);
		if(xor.equals(paritystr)){
			return str.substring(0,_index-3)+"]";
		}
		return "";
	}

	/**
	 * 获取异或值
	 * 
	 * @author aixianshang
	 * @date 2015年9月14日 下午1:31:22
	 * @param str
	 * @return
	 */
	public static String xor(String str) {
		if (StringUtils.isEmpty(str)) {
			return "";
		}
		// 字符下标长度
		int _index = str.length();
		int sum = 0;
		for (int i = 0; i < _index; i++) {
			// 每位字符进行异或求和
			sum = sum ^ str.charAt(i);
		}
		// 把异或求和后的int值转换为16进制字符串
		String s = Integer.toHexString(sum).toUpperCase();
		// 小于2位用0补位
		if (s.length() < 2) {
			s = "0" + s;
		}
		return s;
	}

	// 测试
	public static void main(String[] args) {
		String s = "[FFB3E2d3FF]";
		String s1= "[FFB3E2d3FF0A]";
		String s3 = xorAlgorithm(s);
		String s4 = xorAnalysis(s1);
		System.out.println(s3);
		System.out.println(s4);
	}
}
